Reversible component of machine (5)
I believe the answer is:
rotor
This could be a double definition.
'reversible' is the first definition.
'component of machine' is the second definition.
'rotor' can be an answer for 'component' (I have seen 'Revolving component' mean 'rotor' so perhaps 'component' could also mean 'rotor'). I'm unsure of the 'of machine' bit.
Can you help me to learn more?
(Other definitions for rotor that I've seen before include "Revolving aerofoil" , "It goes round and round (and back and forth)" , "It goes around" , "It lifts helicopter" , "Part of electric motor" .)